Isomerizing hydrocarbons



July 3, 1945. w. E. ROSS ET AL 2,379,749

ISOMERIZING HYDROCARBONS i' Filed March 18, 1944 Readion Zong 1 I i do Feed Frqciionator racrionqi'ors nrmined Cal'algs't Separator Fractiomfl'ors Theodore Vermeulen larly in the proportions genera have sion of substantially pure straight chain paraflin application or these Patented July 3, 1945 William E. Ross and Theodore eley, Calif Vermeulen, Berkassignors to Shell Development Company, San Francisco, Calif., a corporation of Delaware Application March 18, 1944, Serial No. 527,376

paraiiin hydrocarbons, valuable as components of high octane motor fuels as well as starting materials for the production of many organic compounds containing tertiary carbon atoms, much eifort has been expended in attempts to provide practical methods for the conversion of the readily available straight chain paraiiln'hydrocarbons to their branched chain isomers. Processes been disclosed heretofore for the converhydrocarbons, particularly butane and pentane, to their respective branched chain isomers. The processes to the large scale conversion of paraffin hydrocarbons having at least six carbon atoms to the molecule to their respective branched chain isomers is, however, rendered highly impractical due to the difliculty of obtaining these hydrocarbons in suillciently pure form from many of the available sources such as petroleum, natural gasoline, products of thermal and. catalytic hydrocarbon treatments, etc. As is well-known, the narrow boiling hydrocarbon fractions predominating in normally liquid hydrocarbons having the same number of carbon atoms to the straight run hexane or heptane fractions, often comprise other hydrocarbons besides the paraffins, particularly naphthene hydrocarbons which, because of the proximity of their boiling points to those of the parafllns of equal number of carbon atoms, cannot be readily separated therefrom by practical fractionating methods.

Critical amounts of certain naphthenic hydroarbons have the ability to suppress the degradation of paraflin hydrocarbons in the presence of aluminum chloride catalysts. The presence of the naphthenic hydrocarbons, however, particufound in straight run hydrocarbon distillates obtainable from natural sources, renders the straightforward isomerlzation of these fractions, in accordance with molecule such as, for "example.

methods disclosed heretofore, impractical. Laboratory experiments have shown, for example, that the straightforward isomerization of such fractions with aluminum chloride catalysts in the absence of any substantial amount of crack-' closed heretofore. It

- those comprising pentamethylene 14 Claims. (Cl. 260-666) ing generally results in but slight improvement in the octane rating of the treated mixture. The

reaction rates and response of naphthene and paraflin hydrocarbons to changes/in isomerization conditions vary the recovery of naphthenes as substantially pure non-hydroaromatic or aromatic hydrocarbon fractions diincult if not impossible in the isomerization of naphthenic fractions by processes dishas further been found that substantial increase in activecatalyst life can be obtained at the most favorable parafiin isomerization conditions when the naphthenes are removed to at least a substantial degree from the charge.

As stated above, the separation of thenes from narrow boiling hydrocarbon fractionsby such means as fractionation is generally impractical. Their elimination by subjecting the entire charge to an initial dehydrogenation treatment to convert them to aromatics is also impractical, since the dehydrogenating catalysts generally utilized heretofore such as, for example, chromium oxide on alumina, fail to convert the non-hydroaromatic naphthene hydrocarbons, which often comprise at least about one-half of the naphthenes in straight run naphthenic hydrocarbon fractions. A further disadvantage of first subjecting the entire charge to such dehydrogenating catalysts is'the loss sustained due to the conversion of substantial amounts of the nonhydroaromatic naphthene hydrocarbons to undesired products as a'result of side reactions which may comprise polymerization and degradation. It is essential .to economical operation of any process treating such fractions that the naphthenes be recovered; and it'is often desirable to recover them as substantially pure hydroaromatic naphthene or aromatic hydrocarbon fractions. By the term hydroaroxnatic naphthenes" out this specification and claims is meant the naphthene hydrocarbons having a hexamethylene ring, such as cyclohexane and its alkyl derivatives, to distinguish them from the non-hydroaromaticnaphthene hydrocarbons such as rings, for example methyl cyclopentane and dimethyl cycle-- pentane.

An object of the invention is to provide an improved and highly economical process for the vide an improved process for the more eilicient production of branched ormore highlybranched chain parailln hydrocarbons from hydrocarbon fractions comprising straight chain orless branched chain hydrocarbons in admixture with n I 2,319,749 7 UNITED STATES PATENT ,oriucia reatly, thereby-renderin the naphused throughprovide an improved process for ide complex type,

'.naphthene hydrocarbons, with simultaneous recovery of at least asubstantial part of the naphthenes as hydroaromatic or aromatic hydrocarns. Another object 01 the present invention is to the more efflcient production of branched or more highly branched chain parafnn hydrocarbons from hydrocarbon fractions comprising straight chain or less branched chain paraflln hydrocarbons in admixthe invention will become apthereot.

It has been found that of the Ifriedel-Crafts type which have losta substantial part or their activity in the isomerization of parafllnic hydrocarbons still possess ability to catalyze the isomerization' of naphthenes. when such catalysts which are at least partly spent with isomerization catalysts I extraction,

remaining substantially parafllnic hydrocarbons naphthenes. The'resultins hyd oaromatic hydrocarbons together with those originally present in the charge, are removed from the reaction product from the flrst conversion zone by suitable means which may comprise, for example, tractionation, dehydrogenation, hydroiorming, solvent extractive distillation, or the like. The

are contacted with a catalyst comprising a metal halide of the Friedel-Craits type, preferably a fluid-type catalyst, in a second conversion zone under paraflin isomerlzing conditions. At least partly spent catalyst, .drawn from the second conversion zone, is scrubbed with a suitable solvent,

for example, at leasta portion of the paramnic charge to the second conversion zone, therebyrenaphthenic petroleum fractions. Other objects and advantages of parent from the following detailed description naphthene vponents which are regard to their ability to catalyze the psi-emu isomerization are extracted or scrubbed with a suitable solvent, for example, a parafllnic hydrocarbon or hydrocarbon fraction, active catalyst components are removed therefrom by solution leaving a fluid catalyst residue. The resulting fluid catalyst residue, it has been found, though inactive with respect to its ability to catalyze the paraflln isomerizationreaction possess the ability to catalyze the isomerization of naphthenesto a degree enabling theattainment of yields not only exceeding those obtainablewith-the partly spent catalyst from which it was produced but even those obtainable with freshly prepared catalysts of, for example, the hydrocarbon-aluminum halthe isomerization of naphthenic hydrocarbons.

In accordance with the invention naphthenic hydrocarbons, optionally in the presence of other hydrocarbons capable or not of undergoing isomerization under conditions of execution of the process and/or inert gases are contacted with a.

fluid catalyst residue obtained by extracting with a suitable solvent, for example, a parsflinic hydrocarbon or hydrocarbon fraction, '9. catalyst comprising, a metal halide oi the Frledel-Crafts type previously used in the isomerization of paraflin hydrocarbons, thereby separating the catalyst into components active with respect to ability to promote the paraflin isomerization reaction and said catalyst residue. The reaction is preferably executed in the presence of a small amount of a I suitable promoter and the amount of promoter.

of temperature, presthe isoand isomerizing conditions sure and time are correlated to effect merization of naphthenic hydrocarbons.

' In one preferred embodiment of the invention a normally liquid hydrocarbon traction compris-' ing straight chain paraflln hydrocarbons in admoving from the ponents by solution residue. The resulting fluid catalyst residue is passed into the first conversion zone as the The discovery that the catalyst residue which is obtained after scrubbing out catalyst comstill active for paraflin isomerization from an at least partly spent catalyst of the Friedel-Crafts type, and which heretofore has been discarded, enables the selective isomer- I of parafllns onLv an unusually economization of naphthenes in the presence therefore provides not ical method for the eillcient' naphthenes but enables t production isomerization of of high octane parafllnic fractions and the simultaneous as naphthenes of hydrorecovery of naphthenes aromatic structure or as aromatics irom hydrocarbon mixtures non-hydroaromatic naphthenes having the same number 01 carbon atoms to the molecule, with no greater catalyst consumption than heretofore required in theisomeria ation of only theparamn portion of the feed. 1

In order that the invention may be more readily understood. it will be described herein with referheretofore often preferred in ence to the attached drawing forming a part 0! this specification and wherein the single flgure illustrates more or less diagrammatically one form oi'apparatus suitable for the execution of the invention.

A mixture of-saturated hydrocarbons consisting essentially of paraiflns and naphthenes of nonmixture with naphthene hydroc'arbons such as,

for example, a naphthenic hexane or hepta'ne fraction obtained by the fractionation of natural hydroarmoatic and hydroaromatic structure having the same number of carbon atoms to the molecule 'such as, for example, a hexane fraction comprising normal hexane, methyl cyclopentane and cyclohexane, as obtained by fractionation of a i is drawn from naphthenic straight run gasoline, an outside source and forced through valved line i and heater 2 into a flrst reaction zone. The reaction zone may comprise, for example, a reactor 3 provided with suitable stirring means. Itmay at times be advantageous to subject the charge to a fractionation priorto its entry into reactor 3. Thus, when treating anaphthenic hexane fraction boiling, for example, within the range of from about 45 C. to about 0., comprising substantial amounts oi methyl pentanes and/or cyclohexane, all or part of the charge may be passed through valved line 4 into a feed iractionatins zone represented in the drawing by single fractionator I. Within iractionator l the charge may a light-traction boiling, C. and comprising sired, a heavier traction predominating in cyclohexane and boiling, for example, above about 79 C. may be withdrawn as a bottom traction.

catalyst active catalyst comand leaving a fluid catalystisomerizati'on catalyst used therein.

comprising both paramns and catalyst residue obtained lyst 'rated. Separated catalyst valv'ei fline 8. Hydrocarbons are as'za'na whilethe remaining part of the-charge comprising normal hexane and methyl cyclopentane is withdrawn as a side stream and passed through valved line 3 into line 2 leading into reactor 3.

Within reactor 3 the hydrocarbon stream is contacted at naphtheneisomerizing conditions with a fluid catalyst residue obtained, as indicated in greater detail below in the treatment of parafflnic hydrocarbons with the Friedel-Crafts type, lective conversion of non-hydroaromatic naphthenes comprising methyl cyclopentane to hydroa metal halide catalyst of aromatic naphthenes comprising cyclohexane.

Temperatures in reactor 3 in the range of from about C. to about 100 about C. to about 90 C. with a contact time not exceeding the period of time required to obtain equilibrium naphthene conversion, have been found suitable. Hydrogen halide promoters are preferably present in only small amounts, for

thereby effecting the fse-- C. and preferably from prising the hydrogen halide promoter is separated and passed therefrom through valved lines ligand i3 into line 2. Hydrogen halide promoter, when needed, may be introduced into the system Irornj an outside source by means of valved'line I4 leading into line 13. If desired, a light hydrocarbon fraction comprising normal hexane and unconverted methyl cyclopentane may be separated in fractionator H and recycled with the promotor through lines l2, l3 and 2 into reactor 3,

Although but one converter is shown in the drawing asconstituting the naphthene isomerizing zone, it is to be understood that a. plurality of such converters may beused, and fractionation be resorted to between the individual converters to eil'ect the removal of fractions predominating in normal hexane and cyclohexane which are to be example in quantities not exceeding about one per cent of the charge to reactor 3.

The preferential isomerization of non-hydroaromatic naphthenes contained in a naphthenic hexane Iraction tohydroaromatic naphthenes in accordance with the process of the inventionis shown by the following example:

Exsmrm I A hydrocarbon fraction boiling in the range of from 63 to 90 C. and having the following composition:

v Percent Normal hexane l 41 Methyl cyclopentane 38 Cyclohexane l3 7 Benzene 8 was contacted at the naphthene isomerizing conditions indicated in the Table A below with a by scrubbing with a paraihnic hydrocarbon, the spent catalyst produced in the isomerization of a paramn with a .catalyst melt consisting of A1613 dissolved in molten SbCla and separating the resulting residue.

Table 4' Temperature C 100 Catalyst residue-to hydrocarbon feed ratio.. 1:1

Contact time ..minutes 22 HO! added, percent of feed 0. 87 Duration of run hours 305 The results of the operation were as follows:

Cyclohexane in isomerizate as percentage 01' total naphthenes in feed percent. Fbed'treated per pound of catalyst residue charged gallons 7.1 Feed treated per pound of AlCl: :1 catalyst residue chargeddo 116 Reaction products comprising normal hexane, cyclohexane, isohexanes originally present in the feed ,or formed in the process, and entrained cataare passed from reactor 3 into a catalyst separator 8, wherein entrained catalyst is sepais permitted to flow irom separator 3 back into reactor 3., Spent catalyst is withdrawn from reactor 3 by means of passed from separator 3 through line It into a iractionator ll.

Within fractionator H a lighter fraction compart of fractionator II lyst, it is to high isomerization activity may be used, such as line l6. Within fractionator I! a lighter fraction comprising normal hexane is sep rated from a heavier fraction consisting essentially of cyclohexane. 'I'h'e latter fractionator I! through valved line l9 and eliminated from the system as a final product.

The lighter paraflinic fraction separated in fractionator l1 comprising largely normal hexane is passed, at least in part, through valved lines 2| and 22 and through indirect heat exchanger 23 into line 25, provided'with heater 26' and leading into a scrubbing tower 21. Within scrubber 21 the hydrocarbon stream is contacted in the liquid phase with a portion or at least partly spent catalyst emanating from a second conversion zone described more fully below. The hydrocarbon stream comprising extracted catalyst components is passed from scrubber 2! through line 28 and indirect heat exchanger 29 into a second conversion zone. The second conversion zone may comprise, for example, a reactor 3| provided with suitable stirring means. Although but one such reactor is shown in the drawing, it is to be understood that a, plurality of reactors connected in series or in parallel may be used. Within reactor 3| the hydrocarbon stream is subjected to isomer ization conditions eifecting the conversion of straight chain or branched chain paraffin hydrocarbons to branched and more highly branched chain parailin hydrocarbons. The paramn isomerization conditions are obtained by the use of an active ,isomerization catalyst comprising a metal halide o! the Friedel-Crafts type, preferably of a fluid type. Suitable fluid isomerization catalysts comprise catalysts oi the molten salt type such as, for example, a molten salt mixture comprisin aluminum chloride dissolved in antimony trichloride. Although a fluid melt comprising aluminum chloride and antimony trichloride has been chosen as a suitable more active isomerization catabe understood that other catalysts of molten salt mixtures comprising an excess of aluminum chloride and/or aluminum bromide fraction is withdrawn fromv A1ClsNaClKCl, AlClF-NaCl-ZnCh, etc.

Other suitable paraflin isomerizing catalysts comprise: an aluminum halide suspended in a suitable organic solvent, such as for example, a portion of the charge; organo-metal halide complexes such as an aluminum halidehydrocarbon complex comprising suspended free aluminum halide; etc. The temperature to be maintained within reactor 3] will vary with the nature of. the particular catalysts used. When using the highly active catalysts of the molten'salt type, temperatures of from about 80 C. to about 125 0., preferably from about 85 C. to about 100 C., have been found suitable. The parailln conversion step'is effected in the presence of a hydrogen halide promoter. ,The promoter, for example hydrogen chloride, is introduced into reactor 3| in an amount ranging from about 0.5 per cent to about per cent of tlie hydrocarbons charged to this conversion zone.

The advantage of the removal or the naphthenes from the charge to the second conversion zone is illustrated by the following examples showing the effect of increase in naphthene concentration upon catalyst life and the octane rating of the resulting product.

. EXAMPLEII Mixtures of normal hexane and increased amounts of methyl cyclopentane were treated at a temperature of about 85 C. with a fluid catalyst melt consisting of 92.5 per cent by weight oi! SbCla and 7.5 per cent by weight of A1013. The contact time was approximately minutes and the ratiov of catalyst to hydrocarbon chargeaboutlz5 by volume. Hydrogen chloride was added to the charge in the amount of 4 per cent by weight of the hydrocarbon feed. The increase in octane number of the product over that of (the feeds is given in the following table:

Octane number increase of product Weight per cent methyl cyclopentanc in feed EXAMPLE III Weight per cent methyl cyclopentane in feed The above examples, which demonstrate the deleterious effect of the naphthenes upon catalyst life and the octane rating of the hydrocarbon product, clearly show'the advantages obtained by the removal of at least a substantial amount oi the naphthenes from the charge to the peraiiin isomerizing zone.

7 Reaction products comprising methyl pentane. dimethyl butane, some unconverted normal hexane. hydrogen chloride and catalyst are passed from reactor-ll into catalyst separator 32.

Within separation chamber 32 a substantial degree of separation between catalyst melt and hydrocarbon will be eflected. The supematent hydrocarbon layer, which in general will comprise some admixed and dissolved catalyst, is withdrawn from separator 32 and passed through line. 33 into a vaporizing zone. The vaporizing zone may suitably consist of the lower part or a column 34, an intermediate part of which is provided with suitable packing means, baflles, or the like. Within column 34 separation 01' hydrocarbons-from entrained catalyst components is effected with the aid oi. heating coil 35. Since antimony chloride -is relatively volatile, its separation tromthe hydrocarbon within column I is aided by the introduction oi cold hydrocarbon reflux into the upper part oi the column by means of valved line it Hydrocarbon vapors comprising hydrogen chloride promoter are passed from the upper part or column 34 through line 3'! and cooler ll into accumulator 40. Catalyst components consisting essentially of antimony chloride, separated out as a liquid traction withincolumn It, are forced through line ll into reactor 3i. Additional aluminum chloride, required to maintain catalyst composition, is added to the catalyst flowing through, line ll by passing this stream through a suitable vessel containing anhydrous AlCls orby the addition of the halide salt by means of valved conduit 42. a

Hydrocarbons and hydrogen chloride are passed from accumulator ll through line 46 into a, fractionator 41. Within tractionator 41 a lighter fraction comprising hydrogen chloride is separated and recycled through line ll to line 2.. Make-up hydrogen chloride is introduced into line 4! through valved line 49. A valved line 50 leading into line 48 is provided for the introduction of hydrogen, isobutane, or any other suitable paraflin degradation suppressor or gaseous diluent into the system,

, A liquid hydrocarbon fraction comprising isohexanes and normal hexane is withdrawn from the I lower part or fractionator 41 and passed through line II into a final fractionator l2. Within fractionator 52 'a lighter fraction comprising methyl pentanes and substantial amounts of the highly desirable dimethyl butane, is separated as a vapor fraction and eliminated from the system as a final product through valved line 53. A liquid fraction comprising normal hexane is withdrawn from the lower part of iractionator i2 and eliminated from the system through valved line 54. A part or all of the hydrocarbons passing through line it may be passed through valved line 55 into line 2! leading into reactor 3|.

I The process oi the invention is preferably executed in the liquid phase. Pressures sufllciently high to maintain at least a substantial part of the hydrocarbons being treated in'the liquid phase are therefore maintained within reactors 3 and II The catalyst phase, separated out within separator 82, is forced through line 44 into the upper part oi extraction column 21. The portion of catalyst thus introduced into extraction column.

3 will pass countercurrent to the upilow of the Y stream. The composition ever, be provided with found that this erization is obtained as'ra'ne I stream Pulled therewith to reactor 3!. Ancharacteristics. of the by-product catalyst residue other portion of the catalyst comprising compoemanating from scrubber 21.

nents which are" spent, or at least partly spent, with respect to their ability to catalyze the isomerization reaction, remains insoluble in the hy= drocarbon stream and is separated therein as a heavier fluid catalyst residue. The hydrocarbon charge to scrubber 21 is preferably preheated. for example, with the aid of a suitable heat exchanger 2!, to a temperature favorable to the extractionoperation; This temperature will vary with the nature orthe material being treated and the particular catalyst used. In the treatment of paramnic hydrocarbons temperatures in .the approximate range preferably from 50 C. to 100 C. are found suitable. The pressure within column 21 is always sumciently' high to maintain at least a substantial portion of the hydrocarbon stream passing therethrough in the liquid phase. It has been found that the fluid catalyst residue separated within extractor 21 will comprise any hydrocarbon-aluminum chloride complex formed within reactor 3 I. It has also been found that this material is substantially insoluble in the hydrocarbon feed which contributed to its formation and will not undergo decomposition or disintegration to any substantial degree in the extraction zone. whereas the active antimony chloride-aluminum chloride catalyst components ac-' tive for paraiiln' isomerization possess an appreciable degree of solubility in the hydrocarbon oi' the fluid catalyst residue separated within column 21 will vary to some degree with the nature of material treated and operating conditions used. The catalyst residue thus obtained as a by-product of the isomerization operation is found to possess appreciable fluidity and will maintain this fluidity at temperatures substantially below room temperatures. The lower partof column ii may, howa jacket for the passage of a heating medium therethrough to aid in mainitaining the desired temperature conditions there- The rate at which separating chamber part 01' extractor 2! catalyst is withdrawn from 32 and to the upper may vary within the scope or the invention. As pointed out above, however, it is highly advantageous to effect the catalyst withdrawal'at a rate sutiiciently great to prevent the accumulation to any substantial degree of even partially spent catalyst within reactor 3 l- The iiuid catalyst residue separated within scrubber 21 amount of. free n y free aluminum halide therein.

It is to be stressed that not only is the addition of fresh aluminum chloride to the catalyst resiline" into reactor I not to be avoided to mainof from 50 C. to 125 C. and

naphthene-paraflln mixture Although the detailed illustrative description of the invention has been directed to the treatment 01 hydrocarbon mixtures consisting essentially of naphthenes and parafllns having six carbon atoms to the molecule, it is in no wise intended to limit the application of the invention to any particular and may be applied to hydrocarbon mixtures comprising naphthenes and paraflins ofmore than six carbon atoms to the molecule. 7

When treating a naphthenic hydrocarbon fraction comprising hydrocarbons having more than six carbon atoms to the molecule, the removal of the hydroaromatic naphthenes from the products ,emanating from the naphthene isomerizing zone may comprise such stepsas the conversion of the hyd'roaromatic naphthenes to aromatic hydrocarbons, and the separation of the resulting aromatics by solvent extraction, extractive distillation, or other suitable methods.

The high efllciency with which naphthenic hydrocarbons of non-hydroaromatic structure, having more than six carbon atoms to the molecule, are selectively converted to naphthenes of hydroaromatic structure in the presence of paraflinic hydrocarbons is exemplified by the following example:

ExAmeLs IV A dimethylcyclopentane concentrate having the following composition;

was contacted at the naphthene isomerizing conditions indicated in Table 13 below. with a catalyst residue having the following composition:

' .Per cent by weight AlCla 62.8

sbcn 5.5

Carbon as CH2 26.2

' Cl as HG] 4.8

The catalyst residue was obtained by scrubbing with a parafllnic hydrocarbon, the spent catalyst obtained in the isomerization of a parafllnic hydrocarbon with a catalyst melt consisting of aluminum chloride dissolved in'molten antimony trichloride and separating the resulting residue.

. Table'B Temperature C... Cat. residue to hydrocarbon feed ratio 1:1 Contact time "minutes" 18 Vol. of feed/vol. of. catalyst residue/fir--- 3.4 H01 added percent of feed 0.24 Duration of operation .hours 500.

Results of the operation were as follows: Conversion of dlmethylcyclopentane to methylcyclohexane per cent..- 67 Paramns converted (percent of feed) per cent-.. Iiessthanil Feed treate per pound of catalyst residue f s i e-. Reed treated per pound of MCI: in'catalyst residue gallons 240 Potential toluene production. per 'pound of. catalyst residue -..gallons '46 Potential toluene production per pound oi' AlCla in catalyst residue .sallon|-..

prepared AlClspromote the paraflln V haustion in the isomerization ing "hydrocarbons o Conversion of dimethylcyclopentane to methylcyclohexane --per cent.. 65 Feed treated per pound of A1013 in catalyst gallons Potential toluene production per pound of A1013 in catalyst gallons 25 The highly advantageous aspect of the invention is readily apparent from the foregoing example wherein it is shown that the catalyst residue, which already has functioned to exof paraillns was still able to catalyze naphthene isomerization with yields considerably in excess of a freshly drocarbon complex catalyst heretofore generally preferred in large scale operations involving naphthene isomerization..

For the purpose of clarity, all parts of apparatus not essential to a complete description of the invention comprising, for example, pumps, condensers, accumulators, and the like, have beenomitted fromthe drawing. It is to be understood that the apparatus shown may be modifled as apparent to one skilled in the art without departing from the scope of the invention.

Due to the elimination of naphthenes from the hydrocarbon charge, made possible by the process of the invention, the more severe isomerizing conditions within the second conversion zone may be maintained with substantial increase in catalyst life over periods of time substantially in excess of those possible when treating,the originalpharge with its total or onlyslightly modi fled naphthene content. It is to be noted that not only is catalyst life increased, but a parafn ilnic product is obtained with a substantially in- 2. The process for the conversion of naphthenic hydrocarbons of nonhydroaromatic struc- 1 ture having at least six .carbon atoms to the molecule to naphthenes of consisting essentially of paraiilnic with a liquid catalyst comprising a metal'halide of the Friedel-Crafts type at paramn isomerizing conditions until said catalyst is at least partly spent with regard to ability to-promote the paraflln isomerization reaction, separating atleast partly spent catalyst irom hydrocarbon reactants, extracting said separated catalyst with a substantially parafllnic hydrocarbon thereby separating said catalyst by solution into catalyst components soluble in said solvent and a liquid catalyst residue, and contacting hydrocarbons comprising said bons with said catalyst residue at naphthene isomerizing conditions, thereby selectively converting. naphthenes of non-hydroaromatic structure to naphthenes of hydroaromatic structure.

- 3.-The process for selectively isomerizing naphthenes of nonhydroaromatic structure havsisting essentially of a liquid catalyst comprising creased ,octane rating. over' that possible when,

treating straight run naphthenic fractions with less effective removal of naphthene hydrocarbons prior to the paraflln isomerization step. It is thus seen that the process presents not only a substantially improved method for obtaining parafilnic hydrocarbon fractions of substantially increased octane rating, suitable as blending agents for motor fuels and eminently suited as stocks for the alkylation of oleflns and aromatics, but

enables the recovery ofthe naphthene content of the charge as substantially pure hydroaromatic or aromatic hydrocarbon fractions.

We claim as our invention:

1. The process for isomerizing naphthenic hydrocarbons having at least six carbon atoms to the molecule and containing at least five carbon atoms in the-ring to isomeric naphthenic hydro-' carbons having at least six carbon atoms to the molecule and containing at least ilve carbon atoms in the ring which comprisescontacting hydrocarbons consisting essentially of. paramnic hydrocarbons with a liquid catalyst comprising a metal halide of the Friedel-Crafts type at paraflln isomerizing conditions until said catalyst is at least partly spent with regard to ability to isomerization reaction, separating at least partly spentcatalyst from hydrocarbon reactants, extracting said separated catalyst with a substantially solvent, thereby separating said catalyst by solutioninto catalyst components soluble in said sol- -'vent and a liquid catalyst residue, and contactsaid naphthenic parailinlc hydrocarbon with a liquid catalystcomprising a halide of reaction, separating at least ing at,least six carbon atoms to the molecule in admixture with isomerizable paramnichydrocarbons to naphthenes of hydroaromatic structure which comprises contacting hydrocarbons conparaflinic hydrocarbons with Friedel-Crafts type at paraflin isomerizln'g conditions until said catalyst is at least partly spent withregard to ability isomerization reaction, spent catalyst from hydrocarbonreactants, ex"- tracting said separated catalyst with a'substantially paraillnic hydrocarbon solvent, thereby separating said catalyst by solution into catalyst components soluble in said solvent and a liquid catalyst residue, and contacting hydrocarbons.

comprising said naphthenic hydrocarbons with said catalyst residue at naphthene isomerizing conditions, thereby selectively isomerizing naphthenes of nonhydroa'romatic structure to naph thenes of hydroaromatic structure.

I 4. The process for selectively isomerizing naphthenes of nonhydr'oaromatic structure having at least six carbon atoms to the molecule in admixture with isomerizable paraflinic hydrocarbons to, naphthenes of hydroaromatic structure which comprises contacting hydrocarbons consistingessentially of paraillnic hydrocarbons aluminum at paraflin isomerlzing conditions until said catalyst is at least partly spent with regard to ability to promote the-paraflln isomerization partly nt catalyst from hydrocarbon reactants. extract 8 'said'sellarated catalyst with a substantially paranlnic hydrocarbon solvent, thereby separating said catalyst by solution into catalyst components soluble in said solvent and thereby. selectively isomerizing carbon atoms in the ring to hydroaromatic structure which comprises contacting hydrocarbons hydrocarbons solvent,

naphthenic hydrocara metal halide of the to promote the paraflln separating at least partly,

aliquid catalyst residue, .and contacting hydrocarbons comprising said naphthenlc hydrocarbons with said catalyst residue at naphthene' 'isomerlzing conditions, naphthenes of at paraflin isomerizirlg conditions until said catafir t conversion z contacfl rating at least Spent catlyst from hydronaphthenes of hydroaromatic stru carbon reactants, extractin a Separated ing napthenes comprising naphth nonhydroaromatic structure to naphthenes oi. in: at least 6 carbon atoms to the molecule which hydroaromatic structure.- comprises contacting said hydrocarbon mixture 5. The process for selectively isomerizins at isomerizing conditions inafirst conversion zone bons to naphthenes of hydroaromatic, structure thenes 1' non-hydroaromaflc m; which comprises contacting hydrocarbons conthenes of hydroaromatic str sisting essentially of paraflinic hydrocarbons with naphthenes comprising nap a liquid catalyst comprising aluminum chloride m m ti gt mtu from th lyst is at least'partly spent with regard to ability parammc hydrocarbons with a to pr m te the pa amn isom ri ati n r t o comprising a metal halide or the Friedel-Crafts separating at least partly spent catalyst from type t isomerlzjng conditions hydrocarbon reactants, extracting said separated version zone, th

tacting hydrocarbons comprising said naphthenic 2o paramnjc hydrocarbons passing to t structure to naphth n s o hydroaromatiastmcfirst conversion zone to be used the tune. selective naphthene isomerization catalyst.

6. The process f vselectively isomelizing 9. The process for cataiytically isomerizing hynaphthenes of nonhydroaromatic structure hav- I dmarbom comprised in a hydrocarbr'm mixture ing at least six carbon atoms to the molecule in conslstmg essentially f isomerizable straight admixture with isomerizable paramnic hydrccar- 51 m hydrocarbons and naphthene byburns to naphthenes orhydroaromatic structure drocarbonr of antimony and a halide of aluminum at paraflin zone-with selecti isomerizing Conditions Said catalyst at 3 alyst comprising a catalyst residuecbbtained least partly spent with regard to ability to pro- 1n the system, thereby selective mote the paramn isomerization reaction, separmphrhenes r n lyst with a substantially paraiiinic hydrocarbon an aromatic structure frdm solvent, thereby separating said catalyst by soiufir t conversion zone, tion into catalyst components soluble in said sol- I parammc hydrocarbons vent and a liquid catalyst residue, and contacting t comprising halide I hydrocarbons 00111191181118 1 nic y r imng conditions in a second conversion zone, carbons with said 08t81y$tr8$1due napbthene thereby efl'ecting the conversion of straight chain isomerizing conditions. thereby selectively isom to branched chain m wlrhdraw meriZ-ing naphthenes of nonhydroaromatlc sti'ucmg a portion of at least spent catalyst from time to nflpmhenes of hydmammatic structuresaid second conversion zone. scrubbing said por- 7. he process for the conversion f tion of catalyst with said parafllnic hydrocarbons thenichydrocarbons of nonhydroaromatic strucpaggjng to the second conversion zone thereby ture having at least six carbon atoms to the l separating tiv atalyst components by solution molecule to naphthenes of hydroaromatic strucfm a quid, catalyst residue, and passing said ture which comprises contacting-hydrocarbons trim residue to said fir t conversion zone,

' consistin es entially of parsfllnie hydrocarbons to be used therein as said selective naphthene with a liquid catalyst melt comprising aluminum 5:, isomer-matron catalyst chloride and antim ny hl i at Darwin 1c The process 101- catalytically isomerizing merizingconditions until said catalyst is at least hydrocarbons comprised m a vhMmmrrbon p rtly spent with regard to ability to prom ture consisting essentially oi isomerizable the paraflinisomerization reaction, separating at straight chain Mn hydrocarbons and naph- Jeflst p r y p nt catalyst from hydrocarbon thene hydrocarbons oi non-hydroaromatic strucemntfi; extras!!! Said rammed catalyst w ture having at least a carbon atoms to the molea su stantially 'Pora ni hydrocarbon S cule which comprises contacting said hydrocart e y separating said ca yst' r l io into bon mixture at isomerizing conditions in a first h yst components soluble in said o v n and conversion zonewith selective naphthene isomera liquid catalyst residue, and contactlns hr in ization catalyst comprising a catalyst residue obc ns n lns s navhthenic hvdrocertained within the system, thereby selectively coirbons with said catalyst residue at naphthene isomung naphthenes of non-hydroaromaflc m merizin: conditions. thereby selectively conv tturn to naphthenes of hydroaromatic structure. lng naphthezaes oi non-hydroaromaticstructure separating naphthenes comprising naphthenes to naphthen oi hydroaromatic structure. of hydroaromatic structure from the emuence 8. The process for catalytically isomerizina from the first conversion zon contacting the hydrocarbons comprised in a hydrocarbon mix remaining parailinic hydrocarbons with a liquid ture consisting essentially of isomerizable straight type catalyst comprising aluminum chloride at chain paraiiin hydrocarbons and naphthene hylsomcrizing conditions in a second conversion drones-bone of non-hydroaroi'natic structure havlone. thereby electing the conversion 01' straight from said second conversion zone,

hydrocarbons comprised in a hydrocarbon mixture consisting essentially of isomerizable straight chain paraffln hydrocarbons and naphthene hydrocarbons oinon-hydroaromatic structure having at least 6 carbon atoms to the molecule which comprises contacting said hydrocarbon mixture at isorne'rizing conditions in a first conversion zone with selective naphthene isomerization components by solution from ,residue, and passing said catalyst residue to said first conversion zone to be used the hydrocarbon aromatic structure first conversion zone,

paraflinic hydrocarbons with, a liquid catalyst" .melt comprising antimony catalyst comprising a catalyst residue obtained within the system, thereby selectively converting naphthenesof non-hydroaromatic structure to naphthenes of hydroaromatic structure, separating naphthenes comprising naphthenes of hydrofrom the eiiiuence from the contacting the remaining minum chloride at isomerizing conditions in a second conversion zone, thereby eflecting the conversion of straight chain paraflins to branched chain parafiins, withdrawing a portion of at least partly spent catalyst zone, scrubbing said portion of catalyst with said paraiiinic hydrocarbons passing to the second conversion zone thereby separating active catalyst a liquid catalyst therein as said selective naphthene isomerization catalyst.

, 12. The process for the productions! a high octane parafiin hydrocarbon fraction from a mixture ct -saturated hydrocarbons comprising straight chain paraflin hydrocarbons having at least 6 carbon atoms to the molecule and naphthene hydrocarbons of non-hydroaromatic structure having the same number of carbon atoms.

to the molecule which comprises contactihg the hydrocarbon mixture at isomeiization conditions in a first conversion zone with a selective naph thene isomerization catalyst comprising a catalyst residue obtained within the system, thereby effecting the selective conversion of naphthenes of nonhydroaromatic structure to naphthenes ot-hydroaromatic structure, separating naphthenes comprising naphthenes of hydroaromatic structure from the efliuence from the first conversion zone, contacting the. remaining hydrocarbons with a liquid type catalyst comprising a metal halide of the Frieda-Crafts type atisom from said second conversion.

active catalyst components 3 in a first conversion trichloride and alurizationconditions in a second conversion zone,

thereby converting said remaining hydrocarbons.

ing a portion least. partly spent catalyst from said second conversion zone, contacting.

at least a part or said portion 0! catalyst with charge to the second conversion liquid catalyst residue,

catalyst residue as .said selective naphthene- -verting said remaining drocarbon traction residue catalyst in said first conversion zone. 2

13. The process for the production of a high octane paraflin hydrocarbon fraction from a mixture of saturated hydrocarbons comprising straight chain paraflin hydrocarbons having at least .6 carbon atoms eflecting the selective conversion oi naphthenes of non-hydroaromatic strnctureito naphthenes of hydroaromatic structure, separating naphthenes comprising naphthenes of hydroaromatic structure from the eiiiuence from the first conversion zone, contacting the remaining hy ro carbons with a liquid type catalyst comprising a halide of aluminum at isomerization conditions in a second conversion zone, thereby conhydrocarbons to' a high octane paraflin hydrocarbon fraction comprising branched chain paramns, withdrawing a portion of at least partly spent catalyst from said second conversion zone, contacting said portion of catalyst with atleast a part 0! the hydrocarbon charge to the second conversion zone, thereby separating said catalyst into soluble active catalyst components and a liquid catalyst residu and utilizing said liquid catalyst residue as said selective naphthene isomerization catalyst in said first conversion zone.

14. The process for octane paraffin hydrocarbon fraction i'rom a mixture-of saturated hydrocarbons comprising straight chain paraflin hydrocarbons having at least 6 carbon atoms thenehydrocarbons of non-hydroaromatic structure having the same number of carbon atoms to the molecule whi h comprises contacting the hydrocarbon mixture at isomerization conditions in a first conversion zone with a selective naphthene isomerization catalyst comprising a cata mixture aiter comprising antimony trichloride and aluminum chloride at isomerization conditions in a second conversion zone, thereby converting said remaining hydrocarbons to a'highoctane paraiiin by? comprising branched chain paraflins, withdrawing a portion of at least partly spent catalyst from said second conversion zone, contacting said portion of catalyst with a part or the hydrocarbon charge to the second. conversion zone, thereby separating said catalyst into-soluble active catalyst components and a and utilizing said liquid 1 isomerization. catalyst in said conversion s 'rnnonoan vnammumun as said selective naphthene isomerization:

to the molecule and naphthene hydrocarbons of non-hydroaromatic structhe production or a high to the molecule and naphoi lnrdroaromatic.

treatment, contacting the remaining hydrocarbons with a liquid ,catalyst melt at least 

